Adeno-Associated Virus Virion for Gene Transfer to Nervous System Cells

ABSTRACT

The present invention provides a means for transferring a therapeutic gene of interest into a nervous system cell by a highly-efficient and simpler means. More specifically, the present invention provides a recombinant vector that uses an adeno-associated virus (AAV), a method for manufacturing the recombinant vector, and a method for using the recombinant vector. More specifically, recombinant adeno-associated virus virions, which are capable of passing through the brain-brain barrier, for transferring a therapeutic genes of interest into a nervous system cell in a highly-efficient manner, a drug composition containing the recombinant adeno-associated virus virions, a method for manufacturing the recombinant adeno-associated virus virions, and a kit or the like are provided.

TECHNICAL FIELD

The present invention relates to a recombinant adeno-associated virus (rAAV) virion used for gene transfer. More specifically, the present invention relates to a recombinant adeno-associated virus (rAAV) virion, which is capable of passing through a blood-brain barrier for transferring a gene of interest into a nervous system cell with high efficiency, a composition comprising the same, and so on.

BACKGROUND ART

Central nervous system disorders have caused serious public health concerns. The number of patients in Japan with Alzheimer's disease alone, which results in cognitive dysfunction due to the degeneration and loss of nerve cells, is estimated to be more than 600,000. Currently, central nervous system disorders are treated mostly by systemic administration of therapeutic drugs. In systemic administration, however, drugs are usually incapable of passing through the blood-brain barrier and are often inefficient. Thus, many potentially useful therapeutic proteins, etc. cannot be administered systemically.

There are known methods for using an adeno-associated virus (AAV) as a vector derived from a virus for gene therapy (e.g., WO2003/018821, WO2003/053476, WO2007/001010, etc.). However, when gene transfer to a nervous system cell such as in the brain is attempted, it is necessary to consider problems including defensive functions such as the blood-brain barrier, etc., the transduction efficiency to nervous system cells, the expression efficiency, a safer route for administration, and the like.

Nakai H., et al. (Unrestricted hepatocyte transduction with adeno-associated virus serotype 8 vectors in mice. J. Virol. 2005 January; 79(1): 214-24) discloses an example of using a serotype 8 AAV vector AAV8-EF1α (-nlslacZ) expressing a LacZ gene marker with an EF1α promoter, for the purpose of gene transduction to hepatocytes.

Foust K. D., et al. (Intravascular AAV9 preferentially targets neonatal neurons and adult astrocytes. Nat. Biotechnol. 2009 January; 27(1): 59-65) discloses a self-complementary (sc) vector with the coat protein of serotype 9 AAV (AAV9) that expresses a green fluorescent protein (GFP) under the control of a chicken-β-actin hybrid promoter (CB). Duque S., et al. (Intravenous Administration of Self-complementary AAV9 Enables Transgene Delivery to Adult Motor Neurons. Mol. Ther. 2009 July; 17(7): 1187-96) also discloses a self-complementary vector (scAAV9-GFP) with a serotype 9 AAV (AAV9) capsid protein that expresses GFP under the control of the cytomegalovirus immediate-early promoter (CMV) (cf., Table 1 for the summary of the results).

Gene transfer to the brain (including neurons from neonates, astrocytes from adults, etc.) has been performed through intravascular administration of these recombinant AAV9 vectors. However, it is necessary to incorporate a reverse sequence to generate an sc type viral genome, a gene that can be incorporated into the viral genome becomes half as long as a non-sc type viral genome. Specifically, the length of the gene that can be incorporated in the sc type vector is limited to a length as small as 2 kb including the promoter and poly(A) region. By means of this limitation, therapeutic applications of recombinant viral vectors are limited as well.

As described above, various recombinant adeno-associated virus vectors have been produced. However, there are unknown vectors such recombinant AAV vectors that can make use of non-sc form AAV genomes that are capable of passing through the blood-brain barrier in a living subject and as associated with simple administration to enable efficient gene transfer especially to a nervous system cell in the brain, whereby a wider range of therapeutic applications can be expected.

PRIOR ART DOCUMENTS Non-Patent Documents

-   [Non-Patent Document 1] Nakai H., et al. (J. Virol. 2005 January;     79(1): 214-24.) -   [Non-Patent Document 2] Foust K. D., et al. (Nat. Biotechnol. 2009     January; 27(1): 59-65.) -   [Non-Patent Document 3] Duque S., et al. (Mol. Ther. 2009 July;     17(7): 1187-96.)

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

Under the foregoing circumstances, it has been desired to develop a viral vector (virus virion) which can deliver a therapeutic gene of interest to a nerve cell located in brain, spinal cord, etc. of a living subject, especially a nerve cell in the brain, through a simpler administration route with high efficiency, and which can package a non-sc type viral genome to allow the gene of interest to be selected from a wider range of length.

Means for Solving the Problems

As a result of extensive studies, the present inventors have successfully achieved constructing a recombinant adeno-associated virus (rAAV) virion capable of transferring a gene to a nervous system cell with significantly high efficiency through peripheral administration to a subject by modifying a wild type capsid protein for usual single-stranded AAV, and by using the resultant configuration in combination with a recombinant AAV genome containing an oligodendrocyte-specific promoter or a synapsin I promoter, which is nervous system cell-specific.

More specifically, the present invention provides a recombinant adeno-associated virus (rAAV) virion which is capable of transferring a therapeutic gene to a nervous system cell in the brain, spinal cord, etc. of a living subject with high efficiency and is capable of passing through the blood-train barrier in addition to aspects such as a pharmaceutical composition comprising the same.

[1] A recombinant adeno-associated virus virion comprising:

(a) a capsomere which comprises a protein comprising an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 2, 4 or 6, wherein at least one of surface-exposed tyrosine residues in the amino acid sequence is substituted with another amino acid residue, and the protein is capable of forming a virus virion, and

(b) a polynucleotide packaged in said capsomere which comprises a nervous system cell-specific promoter sequence and a nucleotide sequence operably linked to the promoter sequence.

[1a] The virus virion according to [1], wherein the nervous system cell-specific promoter sequence is derived from a nerve cell, glial cell or oligodendrocyte.

[2] The virus virion according to [1], wherein the protein comprises an amino acid sequence in which at least the tyrosine residue at position 445 in SEQ ID NO: 2, the tyrosine residue at position 444 in SEQ ID NO: 4 or the tyrosine residue at position 446 in SEQ ID NO: 6 is substituted.

[3] The virus virion according to claim 1 or 2, wherein the tyrosine residue is substituted with phenylalanine residue.

[4] The virus virion according to any one of [1] to [3], wherein the protein comprises:

the amino acid sequence of SEQ ID NO: 8, 10 or 12, or

an amino acid sequence in which 1 to several amino acids are deleted, substituted, inserted and/or added at positions other than positions 444 to 446 in the amino acid sequence of SEQ ID NO: 8, 10 or 12; and

wherein the protein is capable of forming a virus virion.

[5] The virus virion according to any one of [1] to [4], wherein the 5′ and 3′ ends of the polynucleotide contain the 5′ and 3′ end-inverted terminal repeat (ITR) sequences derived, respectively, from AAV1, AAV2, AAV3 or AAV4.

[6] The virus virion according to any one of [1] to [5], wherein the 5′ and 3′ ends of the polynucleotide contain the nucleotide sequences of SEQ ID NO: 13 and SEQ ID NO: 14, respectively.

[7] The virus virion according to any one of [1] to [5], wherein the polynucleotide has a full length of approximately 2 to 6 kb and is a single stranded DNA which is a sense strand or an antisense strand.

[8] The virus virion according to any one of [1] to [6], wherein the promoter sequence is selected from the group consisting of a synapsin I promoter sequence, a myelin basic protein promoter sequence, a neuron-specific enolase promoter sequence, a calcium/calmodulin-dependent protein kinase II (CMKII) promoter sequence, a tubulin αI promoter sequence, a platelet-derived growth factor β chain promoter sequence, a glial fibrillary acidic protein (GFAP) promoter sequence, a L7 promoter (cerebellar Purkinje cell specific promoter) sequence and a glutamate receptor delta 2 promoter (cerebellar Purkinje cell specific promoter) sequence.

[9] The virus virion according to [7], wherein the promoter sequence comprises the polynucleotide as set forth in SEQ ID NO: 23 or SEQ ID NO: 24.

[10] The virus virion according to [7], wherein the nucleotide sequence operably linked to the promoter sequence encodes a protein selected from the group consisting of an antibody, a nerve growth factor (NGF), a growth factor (HGF), an acidic fibroblast growth factor (aFGF), a basic fibroblast growth factor (bFGF), a glial cell line-derived neurotrophic factor (GDNF), an aromatic amino acid decarboxylase (AADC) and an amyloid β degrading protease (Neprilysin).

[10a] The virus virion according to [7], wherein the nucleotide sequence operably linked to the promoter sequence expresses dsRNA, siRNA, shRNA or miRNA against the aromatic amino acid decarboxylase (AADC) or α-synuclein.

[11] The virus virion according to [9], wherein the antibody is an antibody against aggregated amyloid β protein.

[11a] The virus virion according to [9], wherein the antibody is a single chain antibody against aggregated amyloid β protein.

[11b] The virus virion according to claim 10, wherein the nucleotide sequence is amyloid β degrading protease (Neprilysin).

[12] The virus virion according to any one of [1] to [11], which is capable of passing through the blood-brain barrier of a subject.

[12a] The virus virion according to any one of [1] to [12] for gene transfer to a nerve cell by peripheral administration to a subject.

[12b] The virus virion according to any one of [1] to [12], wherein the subject is a fetus in the maternal body and the gene is transferred to a nerve cell of the fetus by peripheral administration to the maternal body.

[13] The virus virion according to any one of [1] to [12], wherein the virus virion is an adeno-associated virus vector.

[14] A pharmaceutical composition comprising the virus virion according to any one of [1] to [13].

[15] The pharmaceutical composition according to [14], which reduces aggregated amyloid β protein in the brain of a subject.

[15a] The pharmaceutical composition according to [13], which reduces the level of α-synuclein in nerve cells in the brain of a subject.

[16] The pharmaceutical composition according to [14] or [15], which is a therapeutic agent for Alzheimer's disease.

[16a] The pharmaceutical composition according to [14] or [15a], which is useful for the treatment of Parkinson's disease.

[17] A method comprising a step of administering the virus virion according to any one of [1] to [12] peripherally to a subject.

[17a] The method according to [17], wherein the subject is a fetus in the maternal body and the virus virion is peripherally administered to the maternal body.

[18] The method according to [17], which further comprises a step of reducing aggregated amyloid β protein in the brain of a subject.

[18a] The method according to [17a], which further comprises a step of reducing the level of α-synuclein in nerve cells in the brain of a subject.

[19] The method according to [18] for the treatment of Alzheimer's disease.

[19a] The method according to [18a], which is useful for the treatment of Parkinson's disease.

Effects of the Invention

The recombinant viral vector of the present invention is capable of passing through blood-brain barrier and thus capable of transferring a gene to a nervous system cell in the brain via peripheral administration. In addition, the vector of the present invention can select a therapeutic gene of interest from a broader range, especially in length, by using a non-sc type genome. Therefore, by using the rAAV vector of the present invention that packages the viral genome for carrying the gene of interest encoding a useful protein (which may be one or more), e.g., an antibody, neurotrophic factor, etc., the gene can be transferred to a nervous system cell in the brain, etc. of a subject, through a safe administration method such as peripheral administration, etc. For example, the gene encoding α-synuclein, which is associated with Parkinson's disease, the gene encoding the antibody against amyloid β protein aggregate, which causes Alzheimer's disease, etc. can be incorporated into the recombinant vector of the present invention to provide safer therapeutic drugs for these diseases. Furthermore, the method for producing the virus vector of the present invention and/or the kit of the present invention can be used to prepare the rAAV vector for delivering and transducing a gene of interest to a nervous system cell in a brain or the central nervous system, through peripheral administration with high efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows GFP-positive cells in the brain per mouse, using the rAAV virion of the invention.

FIG. 2A shows a picture of the coronal section slice from murine brain tissue after peripheral administration of the yfAAV9-CAG-GFP-containing rAAV vector, and a partially enlarged view. GFP-positive cells are mostly glial cells (arrowhead) (green: GFP, red: NeuN).

FIG. 2B shows a picture of the coronal section slice from murine brain tissue after peripheral administration of the yfAAV9-SynI-GFP-containing rAAV vector, and a partially enlarged view.

FIG. 2C shows a picture of the coronal section slice from murine brain tissue after peripheral administration of the yfAAV9-MBP-GFP-containing rAAV vector, and a partially enlarged view.

FIG. 3 shows GFP-positive cells per 0.04 mm³ of the cerebral cortex, using the rAAV virion of the present invention.

FIG. 4 shows image pictures where nerve cells in which GFP and ChAT in the spinal cord are positive, using the rAAV virion of the present invention, and a partially enlarged view.

FIG. 5 shows an image picture where the results obtained by gene transfer to fetal brain nerve cells through intracardial administration to mother mice using the rAAV virion of the present invention (left), and a partially enlarged view (right).

FIG. 6 shows image pictures where the results of immunostaining of various antibodies in the substantia nigra pars compacta in nerve cells of the mouse brain, by intracardial administration of the yfAAV9-SynI-GFP-miAADC described in Example 3. The primary antibodies used are anti-GFP (left), anti-AADC (center) and anti-TH (right).

MODE FOR CARRYING OUT THE INVENTION 1. Recombinant Adeno-Associated Virus (rAAV) Virion of the Present Invention

In an embodiment, the present invention provides the following rAAV virion defined below:

a recombinant adeno-associated virus virion comprising:

(a) a capsomere which comprises a protein comprising an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 2, 4 or 6, wherein at least one of the surface-exposed tyrosine residues in the amino acid sequence is substituted with another amino acid residue, and the protein is capable of forming a virus virion, and

(b) a polynucleotide packaged in said capsomere which comprises a nervous system cell-specific promoter sequence and a nucleotide sequence operably linked to the promoter sequence.

1.1 Adeno-Associated Virus (AAV)

Naturally occurring adeno-associated virus (AAV) is a non-pathogenic virus. By using this characteristic property, various recombinant viral vectors are constructed and used to deliver a desired gene to achieve gene therapy (see, e.g., WO2003/018821, WO2003/053476, WO2007/001010, Yakugaku Zasshi 126(11) 1021-1028, etc.). A wild type AAV genome is a single-stranded DNA molecule having a full length of approximately 5 kb nucleotides, and is a sense strain or an antisense strain. In general, the AAV genome contains an inverted terminal repeat (ITR) sequence of about a 145 nucleotide length at both 5′ and 3′ ends of the genome. This ITR is known to have various functions including the function as a replication origin of the AAV genome, the function as a packaging signal of this genome into virions, and so on (see, e.g., Yakugaku Zasshi, 126 (11) 1021-1028 supra, etc.). The internal region of the wild type AAV genome flanked by the ITRs (hereinafter the internal region) contains an AAV replication (rep) gene and a capsid (cap) gene. The rep gene and the cap gene encode, respectively, a protein Rep involved in virus replication and a capsid protein capable of forming a capsomere (e.g., at least one of VP1, VP2 and VP3) which is an outer shell of the regular icosahedral structure. For further details, reference is made to, e.g., Human Gene Therapy, 13, pp. 345-354, 2002, Neuronal Development 45, pp. 92-103, 2001, Jikken Igaku, 20, pp. 1296-1300, 2002, Yakugaku Zasshi, 126(11), 1021-1028, Hum. Gene Ther., 16, 541-550, 2005, etc.

Naturally occurring adeno-associated viruses are known to have various serotypes and to exhibit a preferential tropism for target cells to be infected (which is described in, e.g., Gao, G. et al., Curr. Gene Ther. 5:285-297, 2005, Xin, K-Q, et al., J. Virol. 80: 11899-910, 2006, Hellstroem, M., et al., Gene Ther. 16:521-32, 2009, etc.). Preferably, the rAAV vector of the present invention can be prepared from, but not limited to, naturally occurring adeno-associated virus serotype 1 (AAV1), serotype 2 (AAV2), serotype 3 (AAV3), serotype 4 (AAV4), serotype 5 (AAV5), serotype 6 (AAV6), serotype 7 (AAV7), serotype 8 (AAV8), serotype 9 (AAV9), etc. The nucleotide sequences of these adeno-associated virus genomes are known and referred to as the GenBank accession numbers of AF063497.1 (AAV1), AF043303 (AAV2), NC_(—)001729(AAV3), NC_(—)001829.1 (AAV4), NC_(—)006152.1 (AAV5), AF028704.1 (AAV6), NC_(—)006260.1 (AAV7), NC_(—)006261.1 (AAV8) and AY530579 (AAV9), respectively. Among them, the serotypes 2, 3, 5 and 9 are human-derived. According to the present invention, it is particularly preferred to use the nucleotide sequence encoding the capsid protein derived from AAV1, AAV2 or AAV9. AAV1 and AAV9 were reported to have comparatively high infection efficiency on nerve cells (Taymans, et al., Hum Gene Ther 18:195-206, 2007, etc.). AAV2 has already been clinically applied to gene therapy for Parkinson's disease, etc. (Kaplitt, et al., Lancet 369: 2097-2105, 2007, Marks, et al., Lancet Neurol. 7:400-408, 2008, Christine et al., Neurology 73:1662-1669, 2009, Muramatsu, et al., Mol. Ther. 18:1731-1735, 2010, etc.).

1.2. Capsid Proteins in the rAAV Virion of the Present Invention

In the capsid proteins contained in the rAAV virion of the present invention, at least one of the surface-exposed tyrosine residues (e.g., tyrosine residues with an amino acid side chain exposed on the surface of the virus virion) in the VP1 amino acid sequence (SEQ ID NO: 2, 4 or 6) is substituted with another amino acid. Such proteins include those comprising an amino acid sequence having a sequence identity of at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99.1%, at least 99.2%, at least 99.3%, at least 99.4%, at least 99.5%, at least 99.6%, at least 99.7%, at least 99.8%, or at least 99.9%, to the amino acid sequence of SEQ ID NO: 2, 4 or 6, wherein at least one of the surface-exposed tyrosine residues is substituted with another amino acid, and wherein the protein is capable of forming the virus virion. In general, the larger value for the above number is the more preferable. The capsid protein contained in the rAAV virion of the present invention forms capsomeres alone or in combination with the other capsid protein members (e.g., VP2 and/or VP3, etc.). The rAAV virion of the present invention with the AAV genome (or AAV vector genome) packaged in the capsomere can thus be produced. The rAAV of the present invention is capable of passing through the blood-brain barrier in a living subject (including the blood-brain barrier in an immature fetus and neonate and the blood-brain barrier in an established adult). Moreover, the rAAV virion of the present invention can target nerve cells contained in brains, spinal cords, etc. of adults by peripheral administration. As used herein, the term peripheral administration is used to mean administration routes usually understood by those skilled in the art to be peripheral administration, including intravenous administration, intraarterial administration, intrapericardial administration, intramuscular administration, and umbilical intravascular administration (e.g., the target is a fetus), and so on. The amino acid residues which may be replaced with each other include the other residues among the group of the similar amino acid residues (described below), in which the amino acid residues fall. The capsid proteins modified with the interchangeable amino acid residues can be produced by methods known to those skilled in the art, including conventional genetic engineering techniques, etc. For such genetic engineering procedures, reference may be made to, e.g., Molecular Cloning 3rd Edition, J. Sambrook et al., Cold Spring Harbor Lab. Press. 2001, Current Protocols in Molecular Biology, John Wiley & Sons 1987-1997, etc.

In the capsid proteins contained in the rAAV virion of the present invention, at least one of the surface-exposed tyrosine residues, preferably, at positions 252, 273, 445, 701, 705 and 731 in SEQ ID NO: 2 is substituted with another amino acid, preferably with a phenylalanine residue. Preferably, the tyrosine residue at position 445 is substituted with a phenylalanine residue in the amino acid sequence of SEQ ID NO: 2. In the capsid proteins contained in the rAAV virion of the present invention, at least one of the surface-exposed tyrosine residues, preferably, at positions 252, 272, 444, 500, 700, 704 and 730 in SEQ ID NO: 4 is substituted with another amino acid, preferably with a phenylalanine residue. It is preferred that the tyrosine residue at position 444 is substituted with a phenylalanine residue in the amino acid sequence of SEQ ID NO: 4. In the capsid proteins contained in the rAAV virion of the present invention, one or more of at least one of the surface-exposed tyrosine residues, preferably, at positions 252, 274, 446, 701, 705, 706 and 731 in SEQ ID NO: 8 is substituted with another amino acid, preferably with a phenylalanine residue. It is preferred that the tyrosine residue at position 446 is substituted with a phenylalanine residue in the amino acid sequence of SEQ ID NO: 6. The capsomere in the rAAV virion of the present invention may either contain the above protein alone or in further combination with other members (VP2 and/or VP3). According to the present invention, the substitution at the position of the amino acid residue includes the substitution of the amino acid residue at the corresponding position in the VP2 and VP3 from each of the virus serotypes, and preferably, the substitution of such corresponding tyrosine residue with a phenylalanine residue. These modified capsid proteins may be prepared by methods known to those skilled in the art including conventional genetic engineering techniques, etc. For these genetic engineering procedures, reference is made to, e.g., Molecular Cloning, 3rd Edition, etc. The virus virions of the present invention containing these capsid proteins are capable of passing through adult and fetus blood-brain barriers as described above. Preferably, the virus virions containing the functionally equivalent capsid proteins can infect nervous system cells in brains, spinal cords, etc. of adults, through peripheral administration. The term nervous system as used herein refers to the organ system made up of nerve tissues. In the present invention, nervous system cells as a target for gene transfer include at least neurons located in the central nervous system including brains, spinal cords, etc. and may further include glial cells, microglial cells, astrocytes, oligodendrocytes, ependymocytes, cerebrovascular endothelial cells, etc. The ratio of the gene-transferred nerve cells of the gene-transferred nervous system cells is preferably 70% or more, 80% or more, 85% or more, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, 99.5% or more, 99.6% or more, 99.7% or more, 99.8% or more, 99.9% or more, or 100%.

The rAAV virion of the present invention also comprises the amino acid sequence of SEQ ID NO: 8, 10 or 12, or an amino acid sequence, in which one or more amino acids are deleted, substituted, inserted and/or added at positions other than the positions 444 to 446 in the amino acid sequence of SEQ ID NO: 8, 10 or 12, and comprises a protein still capable of forming virus virions. In more detail, the capsid proteins contained in the rAAV virion of the present invention are contained in the capsomere of the rAAV virion of the present invention, alone or in combination with the other capsid protein members (e.g., VP2 and/or VP3, etc.), and the AAV genome (or the recombinant AAV vector genome) is packaged inside the capsomere. In the deletion, substitution, insertion and addition of amino acids described above, two or more modifications may be made at the same time. Examples of these proteins include the proteins having the amino acid sequence of SEQ ID NO: 8, 10 or 12, or those containing an amino acid sequence, in which, e.g., 1 to 50, 1 to 40, 1 to 39, 1 to 38, 1 to 37, 1 to 36, 1 to 35, 1 to 34, 1 to 33, 1 to 32, 1 to 31, 1 to 30, 1 to 29, 1 to 28, 1 to 27, 1 to 26, 1 to 25, 1 to 24, 1 to 23, 1 to 22, 1 to 21, 1 to 20, 1 to 19, 1 to 18, 1 to 17, 1 to 16, 1 to 15, 1 to 14, 1 to 13, 1 to 12, 1 to 11, 1 to 10, 1 to 9 (1 to several), 1 to 8, 1 to 7, 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, or 1 amino acid residue is deleted, substituted, inserted and/or added at positions other than the positions 444 to 446 in the amino acid sequence of SEQ ID NO: 8, 10 or 12, and wherein the protein is capable of forming a virus virion. In general, the smaller the number of the above-described amino acid residues to be deleted, substituted, inserted and/or added is, the more preferred. The rAAV virion produced in the present invention can pass through adult and fetus blood-brain barriers as described above, which enables gene transfer to nerve cells in the brain, spinal cord, etc., preferably through peripheral administration. Furthermore, the rAAV virion of the present invention can transfer a gene to a nervous system cell contained in a fetal brain, spinal cord or the like in a maternal body by peripheral administration to the maternal body. These modified capsid proteins can be prepared in accordance with methods known to those skilled in the art, including conventional genetic engineering techniques, etc.

Examples of the amino acid residues which are interchangeable in the protein (polypeptide) of the present invention are given below. The amino acid residues in the same group are interchangeable. Group A: leucine, isoleucine, norleucine, valine, norvaline, alanine, 2-aminobutanoic acid, methionine, o-methylserine, t-butylglycine, t-butylalanine and cyclohexylalanine; Group B: aspartic acid, glutamic acid, isoaspartic acid, isoglutamic acid, 2-aminoadipic acid and 2-aminosuberic acid; Group C: asparagine and glutamine; Group D: lysine, arginine, ornithine, 2,4-diaminobutanoic acid and 2,3-diaminopropionic acid; Group E: proline, 3-hydroxyproline and 4-hydroxyproline; Group F: serine, threonine and homoserine; and Group G: phenylalanine and tyrosine.

The aforesaid capsid proteins VP1, VP2 and/or VP3 contained in the rAAV virion of the present invention can be encoded by one or more polynucleotides. Preferably, the capsid proteins in the present invention are all encoded by one polynucleotide. More preferably, the capsid proteins are encoded by the polynucleotide of SEQ ID NO: 7, 9 or 11.

The polynucleotides which encodes the capsid proteins contained in the rAAV virion of the present invention encode proteins that are functionally equivalent to the capsid proteins capable of forming the recombinant virus virion of the present invention. Such polynucleotides include, for example, a polynucleotide sequence of SEQ ID NO: 7, 9 or 11, or a polynucleotide sequence containing SEQ ID NO: 7, 9 or 11, in which, e.g., at least one (e.g., 1 to 50, 1 to 40, 1 to 30, 1 to 25, 1 to 20, 1 to 15, 1 to 10, 1 to 9 (1 to several), 1 to 8, 1 to 7, 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2 and 1) nucleotide is deleted, substituted, inserted and/or added, and said polynucleotide encoding a protein comprising the amino acid sequence of SEQ ID NO: 8, 10 or 12, and a protein comprising an amino acid sequence in which 1 or more amino acids are deleted, substituted, inserted and/or added at positions other than positions 444 to 446 in the amino acid sequence of SEQ ID NO: 8, 10 or 12, and wherein the protein is capable of forming a virus virion. In these deletion, substitution, insertion and/or addition, two or more modifications may be made at the same time. The rAAV virion of the present invention comprising the capsid protein encoded by the polynucleotide is capable of passing through the blood-brain barriers of the adult and fetus, as described above. Preferably, the rAAV virion of the present invention can transfer a gene to nervous system cells contained in the adult brain, spinal cord, etc. through peripheral administration. The rAAV virion of the present invention can also transfer genes to nervous system cells contained in the fetal brain, spinal cord, etc. in the maternal body through peripheral administration to the maternal body. In general, the smaller number of the nucleotides that are deleted, substituted, inserted and/or added as described above is, the more preferred. Such a polynucleotide may include, for example, a polynucleotide which is hybridizable under stringent hybridization conditions to SEQ ID NO: 7, 9 or 11 or its complementary sequence and encodes a protein capable of forming the recombinant virus virion of the present invention (e.g., a protein comprising the amino acid sequence of SEQ ID NO: 8, 10 or 11, or an amino acid sequence in which 1 or more amino acids are deleted, substituted, inserted and/or added at positions other than the positions 444 to 446 in the amino acid sequence of SEQ ID NO: 8, 10 or 12).

The hybridization may be performed by well-known methods or methods modified therefrom, for example, methods described in Molecular Cloning (3rd Edition, J. Sambrook et al., Cold Spring Harbor Lab. Press. 2001), etc. When commercially-available libraries are used, the hybridization may be performed by the methods described in instructions provided by manufacturers, etc. As used herein, the term “stringent conditions” may be any of low stringent conditions, moderate stringent conditions and high stringent conditions. The term “low stringent conditions” refers to conditions of, for example, 5×SSC, 5×Denhardt's solution, 0.5% SDS, 50% formamide at 32° C. The term “moderate stringent conditions” refers to conditions of, for example, 5×SSC, 5×Denhardt's solution, 0.5% SDS, 50% formamide at 42° C. The term “high stringent conditions” refers to conditions of, for example, 5×SSC, 5×Denhardt's solution, 0.5% SDS, 50% formamide at 50° C. Under these conditions, a DNA with higher homology is expected to be obtained efficiently at higher temperatures, although multiple factors are involved in hybridization stringency including temperature, probe concentration, probe length, ionic strength, time, salt concentration and others, and one skilled in the art may appropriately select these factors to achieve similar stringency.

The polynucleotide which is hybridizable include polynucleotides having, e.g., 70% or higher, 80% or higher, 90% or higher, 91% or higher, 92% or higher, 93% or higher, 94% or higher, 95% or higher, 96% or higher, 97% or higher, 98% or higher, 99% or higher, 99.1% or higher, 99.2% or higher, 99.3% or higher, 99.4% or higher, 99.5% or higher, 99.6% or higher, 99.7% or higher, 99.8% or higher or 99.9% or higher identity, to the nucleotide sequence of SEQ ID NO: 7, 9 or 11, as calculated using homology search software, such as FASTA and BLAST using default parameters. In general, the larger numerical value of the homology above is the more preferred.

The identity between amino acid sequences or polynucleotide sequences may be determined using the algorithm BLAST by Karlin and Altschul (Proc. Natl. Acad. Sci. USA, 87: 2264-2268, 1990; Proc. Nail Acad. Sci. USA, 90: 5873, 1993). Programs called BLASTN and BLASTX based on the BLAST algorithm have been developed (Altschul S. F. et al., J. Mol. Biol. 215: 403, 1990). When a nucleotide sequence is analyzed using BLASTN, the parameters are, for example, score=100 and wordlength=12. When an amino acid sequence is analyzed using BLASTX, the parameters are, for example, score=50 and wordlength=3. When BLAST and Gapped BLAST programs are used, default parameters for each of the programs are employed.

The Rep proteins used in the present invention may have a sequence identity of the same value as the above and may contain deletion, substitution, insertion and/or addition in the same number of the amino acid residues as the above, as far as they have known functions with the functionally equivalent level, including the function of recognizing the ITR sequence to perform genome replication depending on the sequence, the function of recruiting and packaging wild type AAV genome (or rAAV genome) into the virus virion, the function of forming the rAAV virion of the present invention, etc. The functionally equivalent level includes a range as described above for the specific activity. In the present invention, the Rep protein derived from known AAV3 is preferably used. More preferably, the protein having the amino acid sequence set forth in SEQ ID NO: 16 is used.

The polynucleotide encoding the Rep proteins used in the present invention may have a sequence identity of the same value as the above and may contain deletion, substitution, insertion and/or addition of the same number of the amino acid residues as the above, as far as it has known functions with the functionally equivalent level, including the function of recognizing the ITR sequence to perform genome replication depending on the sequence, the function of recruiting and packaging wild type AAV genome (or rAAV genome) into the virus virion, the function of forming the rAAV virion of the present invention, etc. The functionally equivalent level includes a range as described above for the specific activity. In the present invention, the rep gene derived from AAV3 is preferably used. More preferably, the polynucleotide having the nucleotide sequence set forth in SEQ ID NO: 15 is used.

In one embodiment of the present invention, the capsid proteins VP1 and the like (VP1, VP2 and/or VP3) encoded by the internal region of wild type AAV genome described above and the Rep proteins are provided in such a form that the polynucleotide encoding them is incorporated into the AAV helper plasmid of the present invention. The capsid proteins (VP1, VP2 and/or VP3) and Rep proteins used in the present invention may be incorporated into 1, 2, 3 or more plasmids, if necessary. Optionally, at least one of these capsid proteins and Rep proteins may be incorporated into the AAV genome. In the present invention, it is preferred that the capsid proteins VP1 and the like (VP1, VP2 and/or VP3) and Rep proteins are all encoded by one polynucleotide and provided as the AAV helper plasmid. Reference may be made to, e.g., EXAMPLES hereinafter.

1.3. rAAV Genome of the Present Invention

The recombinant adeno-associated virus genome packaged into the rAAV virion of the present invention (hereinafter the rAAV genome of the present invention) can be produced by replacing the polynucleotide in the internal region between the ITRs located at the 5′ and 3′ sides of a wild type genome (namely, one or both of the rep gene and cap gene), with a gene cassette comprising a polynucleotide (therapeutic gene) encoding the protein of interest and a promoter sequence for transcribing the polynucleotide, etc. It is preferred that the ITRs at the 5′ and 3′ sides are located at the 5′ and 3′ ends of the AAV genome, respectively. Preferably, in the rAAV genome of the present invention, the ITRs located at the 5′ and 3′ ends include the ITR at the 5′ side and the ITR at the 3′ side contained in the AAV1, AAV2, AAV3 or AAV9 genome. Particularly preferably, the virus genome packaged into the rAAV virion of the present invention is the polynucleotide of SEQ ID NO: 13 for the ITR at the 5′ side and the polynucleotide of SEQ ID NO: 14 for the ITR at the 3′ side. In general, the ITR portion takes the sequence wherein the complementary sequence is easily replaced (flip and flop structure), and the 5′ to 3′ direction may be reversed in the ITR contained in the rAAV genome of the present invention. In the rAAV genome of the present invention, the length of the polynucleotide (i.e., therapeutic gene) which is replaced for the internal region is preferably similar to the length of parent polynucleotide from a practical viewpoint. Specifically, it is preferred that the rAAV genome of the present invention has almost the same size in full length as 5 kb, which is a full length of the wild type, for example, about 2 to 6 kb, preferably about 4 to 6 kb. When the length of transcription regulatory region including a promoter, polyadenylation, etc. is deduced (assuming that the length is e.g., about 1 to 1.5 kb), the size of a therapeutic gene incorporated into the rAAV genome of the present invention is preferably about 0.01 to 3.7 kb, more preferably, about 0.01 to 2.5 kb, and most preferably, about 0.01 to 2 kb, in length, but not limited thereto. Two or more therapeutic genes of about 0.01 to 1.5 kb may also be co-incorporated by known techniques using, e.g., a known internal ribosome entry site (IRES) sequence, as far as the full length of the rAAV genome is within the range described above.

In general, the viral genome packaged in a recombinant adeno-associated virus virion involves a problem that it takes time (several days) until the gene of interest in the genome is expressed, because the genome is single-stranded. To solve the problem, it is attempted to design a therapeutic gene introduced to be self-complementary (called a self-complementary (sc) vector), thereby to promote the expression after infection with the virus vector. In this case, the length of a therapeutic gene described above should be designed to be almost half the length of non-sc genome vector, since it is necessary to contain an inverted sequence to produce a double strand. More specifically, in case of converting a recombinant viral genome to the sc type, the length of a gene of interest that can be incorporated is designed to be approximately 2 kb, including the regions required for a promoter, polyadenylation, etc. Details for specific procedures are described in, e.g., Foust K. D., et al. supra (Nat. Biotechnol. 2009 January; 27(1): 59-65, Non-Patent Document 3), etc. In the present invention, when the length of a gene of interest is short, the sc genome vector may also be used. That is, the rAAV genome used in the present invention may be a non-sc type or a sc type. In the case of the sc type, the whole expression cassette containing a gene of interest or a part thereof can form a double-stranded DNA.

In order to express a polypeptide of interest in the rAAV genome of the present invention, a polynucleotide sequence encoding the polypeptide is operably combined with various known promoter sequences. However, when using a rAAV vector carrying, for example, a CMV promoter, which is a usually available and strong promoter, most of the genes of interest were introduced in glia-like cells, not in nerve cells, in the adult subject (cf., e.g., Example 1 herein below). Therefore, the promoter sequence used in the rAAV virion of the present invention is to be specific to nervous system cells. As defined above, the term nervous system as used herein refers to the organ system made up of nerve tissues. In the present invention, the nervous system cell-specific promoter sequences used in the present invention are derived from, e.g., nerve cells, glial cells, oligodendrocytes, cerebrovascular endothelial cells, microglial cells, ependymocytes, etc., but not limited thereto. Specific examples of such promoter sequences include, but are not limited to, a synapsin I promoter sequence, a myelin basic protein promoter sequence, a neuron-specific enolase promoter sequence, a glial fibrillary acidic protein promoter sequence, a L7 promoter sequence (cerebellar Purkinje cell specific promoter) and a glutamate receptor delta 2 promoter (cerebellar Purkinje cell specific promoter). In the rAAV virion of the present invention, promoter sequences such as a calcium/calmodulin-dependent protein kinase II (CMKII) promoter, a tubulin αI promoter, a platelet-derived growth factor β chain promoter, etc. may also be used. These promoter sequences may be used alone or in optional combination of two or more thereof. Particularly preferred are the synapsin I promoter sequence and the myelin basic protein promoter sequence. The rAAV genome of the present invention may further contain known sequences such as an enhancer sequence which assists in transcription of mRNA, translation into a protein, etc., a Kozak sequence, an appropriate polyadenylation signal sequence, etc.

A therapeutic gene of interest is incorporated into the rAAV genome of the present invention. The therapeutic gene may encode a protein used to treat various diseases. The protein encoded may be one or more, while the rAAV genome to be packaged should be approximately 5 kb or less in length (approximately 4.7 kb or less except for the ITR region), including the gene of interest. When the rAAV genome to be packaged is, for example, the non-sc type, the length of the gene of interest incorporated in the rAAV genome is substantially limited to approximately 3.5 kb or less; when the genome is in the sc type, the length is further limited to a half length of the above. Accordingly, in a further embodiment, a polynucleotide encoding a protein consisting of a short polypeptide is preferably used for a therapeutic gene of interest. Examples of such proteins include, but not limited to, an antibody (including an antigen-binding site, Fab, Fab2, a single chain antibody (scFv), etc.), nerve growth factor (NGF), growth factor (HGF), acidic fibroblast growth factor (aFGF), brain-derived neurotrophic factor (BDNF), neurotrophins NT-3 and NT-4/5, ciliary neurotrophic factor (CNTF), glial cell line-derived neurotrophic factor (GDNF), neurturin, any one of the heregluin/neuregulin/ARIA/neu differentiation factor (NDF) family of agrin, semaphorins/collapsins, netrin-1 and netrin-2, basic fibroblast growth factor (bFGF), glial cell line derived neurotrophic factor (GDNF), aromatic amino acid decarboxylase (AADC), amyloid β degrading protease (Neprilysin), etc. Genes associated with metabolic enzyme diseases that cause neurological disorders (e.g., mucopolysaccharidosis including Gaucher's disease, amino acid metabolism abnormality including homocystinuria, lipid metabolism abnormalities including metachromatic leukodystrophy, etc.) may be incorporated as well and examples of the genes include the genes encoding glucocerebrosidase, cystathionine, β-synthase, arylsulfatase A, etc.

In a still further embodiment of the present invention, the class of antibody encoded by the rAAV genome of the present invention includes, but not particularly limited to, an antibody of any isotype of IgG, IgM, IgA, IgD, IgE, etc. However, it should be noted that the length of the polynucleotide encoding the antibody is practically limited. As used herein, the term “antibody” means to include any antibody fragment or derivative thereof, and includes, for example, Fab, Fab′2, CDR, a humanized antibody, a chimeric antibody, a multifunctional antibody, a single chain antibody (ScFv), etc. In the present invention, the polynucleotide encoding a single chain antibody (ScFv) is preferably used as the therapeutic gene of interest.

The protein encoded by the rAAV genome of the present invention may contain protein variants with insertion, deletion, substitution and/or addition of amino acid residues by genetic engineering, as far as the protein performs the intended functions. In the insertion, deletion, substitution and/or addition, two or more modifications may be made on these protein variants at the same time. Preferably, these protein variants have functions equivalent to those of their parent proteins (e.g., the antigen-binding ability). These protein variants preferably include proteins consisting of, e.g., the amino acid sequence of anti-amyloid β protein (Aβ) single chain antibody (scFv), in which, e.g., 1 to 50, 1 to 40, 1 to 39, 1 to 38, 1 to 37, 1 to 36, 1 to 35, 1 to 34, 1 to 33, 1 to 32, 1 to 31, 1 to 30, 1 to 29, 1 to 28, 1 to 27, 1 to 26, 1 to 25, 1 to 24, 1 to 23, 1 to 22, 1 to 21, 1 to 20, 1 to 19, 1 to 18, 1 to 17, 1 to 16, 1 to 15, 1 to 14, 1 to 13, 1 to 12, 1 to 11, 1 to 10, 1 to 9 (1 to several), 1 to 8, 1 to 7, 1 to 6, 1 to 5, 1 to 4, 1 to 3, 1 to 2, or 1 amino acid residue is deleted, substituted, inserted and/or added, while the protein has the antigen-binding ability equivalent to that of the parent proteins. In the present invention, the term “having equivalent functions” is intended to mean to have the antibody-binding ability that the specific activity is in the range of, e.g., 0.01 to 100-fold, preferably approximately 0.5 to 20-fold, and more preferably, approximately 0.5 to 2-fold, but is not limited thereto.

The therapeutic gene of interest which is incorporated into the rAAV genome of the present invention may be a polynucleotide that alters (e.g., destroys or diminishes) the functions of targeted endogenous genes, including an antisense molecule, ribozyme, interfering RNA (iRNA) or microRNA (miRNA), or a polynucleotide that alters (e.g., down-regulates) the expression levels of the endogenous proteins. The genes to be targeted are those responsible for various diseases and include, but not limited to, a gene encoding α-synuclein associated with Parkinson's diseases, various known oncogenes that cause cancers. To effectively suppress the expression of a gene of interest using, e.g., an antisense sequence, the length of the antisense nucleic acid is preferably at least 10 nucleotides, 15 nucleotides or more, 20 nucleotides or more, 100 nucleotides or more, and more preferably, 500 nucleotides or more. Usually, the length of an antisense nucleic acid to be used is shorter than 5 kb, and preferably, shorter than 2.5 kb.

By using a ribozyme, the mRNA for the target protein can be specifically cleaved to down-regulate the expression of the protein. For the design of such a ribozyme, reference may be made to various known publications (cf., e.g., FEBS Lett. 228: 228, 1988; FEBS Lett. 239: 285, 1988; Nucl. Acids. Res. 17: 7059, 1989; Nature 323: 349, 1986; Nucl. Acids. Res. 19: 6751, 1991; Protein Eng 3: 733, 1990; Nucl. Acids Res. 19: 3875, 1991; Nucl. Acids Res. 19: 5125, 1991; Biochem. Biophys. Res. Commun. 186: 1271, 1992, etc.).

The term “RNAi” is intended to refer to a phenomenon that when a double stranded RNA with a sequence identical or similar to the target gene sequence is introduced into cells, expression of both the foreign gene introduced and the endogenous target gene is down-regulated. The RNA used herein includes, for example, double-stranded RNA of 21 to 25 nucleotides in length that triggers RNA interference, such as dsRNA (double strand RNA), siRNA (small interfering RNA), shRNA (short hairpin RNA) or miRNA (microRNA). These RNAs may be locally delivered to a desired site by a delivery system using liposomes, or a vector that generates the double-stranded RNA described above may be used for local expression thereof. Methods for producing or using such double-stranded RNA (dsRNA, siRNA or shRNA) are known from many publications (see, e.g., Japanese National Publication (Tokuhyo) 2002-516062, US 2002/086356A, Nature Genetics, 24(2), 180-183, 2000 February; Genesis, 26 (4), 240-244, 2000 April; Nature, 407:6802, 319-20, 2002 Sep. 21; Genes & Dev., Vol. 16 (8), 948-958, 2002 Apr. 15; Proc. Natl. Acad. Sci. USA, 99(8), 5515-5520, 2002 Apr. 16; Science, 296(5567), 550-553, 2002 Apr. 19; Proc Natl. Acad. Sci. USA, 99: 9, 6047-6052, 2002 Apr. 30; Nature Biotechnology, Vol. 20 (5), 497-500, 2002 May; Nature Biotechnology, Vol. 20 (5), 500-505, 2002 May; Nucleic Acids Res., 30:10, e46, 2002 May 15, etc.).

As used herein, the terms “virus virion,” “virus or viral vector” and “viral particle” are interchangeably used, unless otherwise indicated.

As used herein, the term “polynucleotide” is interchangeably used with “nucleic acid,” “gene” or “nucleic acid molecule,” which is intended to mean a nucleotide polymer. As used herein, the term “nucleotide sequence” is used exchangeably with “nucleic acid sequence” or “nucleotide sequence,” which is represented by a sequence of deoxyribonucleotides (abbreviated as A, G, C, and T). For example, the “polynucleotide comprising the nucleotide sequence of SEQ ID NO: 1 or a fragment thereof” is intended to mean a polynucleotide comprising a sequence shown by the respective deoxynucleotides A, G, C and/r T of SEQ ID NO: 1, or a fragment thereof.

Each of “viral genome” and “polynucleotide” used in the present invention may exist in the form of a DNA (e.g., cDNA or genomic DNA), respectively, and may also be in the form of an RNA (e.g., mRNA). Each of the viral genome and the polynucleotide as used herein may be a double stranded or single stranded DNA. Single-stranded DNA or RNA may be a coding strand (also known as a sense strand) or a non-coding strand (also known as an anti-sense strand). Regarding the explanation herein for placing a promoter, a gene of interest, polyadenylation signal, etc. in the gene that are encoded by the rAAV genome, if the rAAV genome is a sense strand, the strand itself is described and if it is an antisense strand, its complementary strand is described, unless otherwise specified.

As used herein, the terms “protein” and “polypeptide” are interchangeably used and intended to mean a polymer of amino acids. The polypeptide as used herein is represented in accordance with conventional peptide designation, in which the N-terminus (amino terminus) is at the left hand and the C-terminus (carboxyl terminus) at the right hand. The partial peptide in the polypeptide of the present invention (in case, briefly referred to as the partial peptide of the present invention) includes a partial peptide of the polypeptide of the present invention described above, and preferably having the same properties as those of the polypeptide of the present invention.

As used herein, the term “plasmid” means various known gene elements, for example, a plasmid, phage, transposon, cosmid, chromosome, etc. The plasmid can be replicated in a particular host and transfer gene sequences between cells. As used herein, the plasmid contains various known nucleotides (DNA, RNA, PNA and a mixture thereof) and may be a single strand or a double strand, and preferably a double strand. As used herein, the term “rAAV vector plasmid” is intended to include a double strand formed by rAAV vector genome and its complementary strand, unless otherwise stated. The plasmid used in the present invention may be linear or circular.

The therapeutic gene of interest which is incorporated in the rAAV genome of the present invention is transferred to a nervous system cell with a higher efficiency than before and then incorporated into the genome of the cell. The gene can be transferred to a larger number of nerve cells, which count is approximately 10 times or more, approximately 20 times or more, approximately 30 times or more, approximately 40 times or more, or approximately 50 times or more, when using the rAAV vector of the present invention, as compared to using a conventional rAAV vector. The number of nerve cells carrying the gene transferred thereto can be determined, e.g., by producing an rAAV virion which has a packaged rAAV vector genome with any marker gene incorporated therein, administering the rAAV virion to an animal, and then measuring the number of nervous system cells which express the marker gene (or marker protein) incorporated in the rAAV vector genome. The marker gene to be used is selected from known genes. Examples of such marker genes include LacZ gene, green fluorescence protein (GFP) gene, light emitting protein gene (firefly luciferase, etc.), etc.

In the present invention, an rAAV virion which has an rAAV vector genome packaged can pass through the blood-brain barrier in a living subject. Thus, the therapeutic gene of interest can be transferred to nervous system cells in the brain, spinal cord, etc. of the subject, through peripheral administration to the subject. In case that the rAAV genome of the present invention is a non-sc type, the promoter and the gene of interest may be chosen from a broader range of length. A plurality of the genes of interest may be used as well.

As use herein, the term “packaging” refers to the events including production of single-strand viral genomes, assembly of coat (capsid) proteins, encapsidation of viral genomes, and the like. When an appropriate plasmid vector (normally, a plurality of plasmids) is introduced into a cell line that allows packaging under an appropriate condition, recombinant viral particles (i.e., virus virions, viral vectors) are constructed and secreted into the culture.

2. Production of the rAAV Virion of the Present Invention

In a still further embodiment of the present invention, the invention provides a method for producing the rAAV virion of the present invention. The method may comprise the step of transfecting a cultured cell with: (a) a first polynucleotide which encodes the capsid protein of the present invention (generally called an AAV helper plasmid), and (b) a second polynucleotide (carrying a therapeutic gene of interest) to be packaged in the rAAV virion of the present invention; and may further include the step of transfecting the cultured cell with (c) a plasmid encoding an adenovirus-derived factor, also referred to as an adenovirus (AdV) helper plasmid, or the step of infecting the cultured cell with an adenovirus. The method may also include the step of culturing the transfected cultured cell and collecting the recombinant adeno-associated virus vector from culture supernatant. This method is already known and also used in EXAMPLES below.

Preferably, the method for producing the rAAV virion of the present invention comprises transfecting a cultured cell with: (a) a first polynucleotide encoding a protein comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 8, 10 and 12, and (b) a second polynucleotide comprising a polynucleotide carrying a nervous system cell-specific promoter sequence and a polynucleotide operably linked to the promoter sequence between the nucleotide sequence of SEQ ID NO: 13 and the nucleotide sequence of SEQ ID NO: 14. The first and the second polynucleotides include, for example, the combinations of the polynucleotides as listed in TABLE 1 of EXAMPLES.

Preferably, the nucleotide encoding the capsid protein of the present invention in the first polynucleotide is operably linked to a known promoter sequence that can work in a cultured cell. Examples of such a promoter sequence include cytomegalovirus (CMV) promoter, EF-1α promoter, SV40 promoter, etc., which may be suitably used. The polynucleotide may further contain a known enhancer sequence, Kozak sequence, poly(A) addition signal sequence, etc. appropriately.

The second polynucleotide contains a therapeutic gene at a location operable with the nervous system cell-specific promoter. The polynucleotide may appropriately contain a known enhancer sequence, Kozak sequence, poly(A) addition signal sequence, etc. The first polynucleotide may further contain a cloning site that can be cleaved by various known restriction enzymes downstream from the nervous system cell-specific promoter sequence. A multicloning site containing a plurality of restriction enzyme sites is more preferred. A person skilled in the art may incorporate a therapeutic gene of interest at the downstream of the nervous system cell-specific promoter sequence, in accordance with known genetic engineering procedures. For such genetic engineering procedures, see, e.g., Molecular Cloning 3rd Edition, J. Sambrook et al., Cold Spring Harbor Lab. Press. 2001, etc.

Since an AAV is a helper-dependent virus, it is necessary to co-infect a virion-producing cell (cultured cell) with a helper virus (e.g., adenovirus, herpes virus or vaccinia) upon infection in order to produce the rAAV virion of the present invention. Without co-infection with a helper virus, the viral genome is inserted into a host cell chromosome but any infectious AAV virion derived from the viral genome inserted is not produced. When the host with the inserted viral genome is infected with a helper virus, the infectious AAV virion from the inserted genome may be produced. AAV itself may infect cells from different species while it is required that a helper virus be the same species as a host cell. For example, human AAV can be replicated in canine cells co-infected with canine adenovirus.

In producing the rAAV virion of the present invention, the first and the second polynucleotides as described above can be co-introduced into cultured cells, using a helper virus plasmid (e.g., adenovirus, herpesvirus or vaccinia). Preferably, the production method of the present invention further comprises the step of introducing an adenovirus (AdV) helper plasmid. The AdV helper plasmid encodes proteins such as E1a, E1b, E2a, E4 orf4, etc. which are required for AAV genome replication, etc. Alternatively, a recombinant viral or non-viral vector (e.g., plasmid, episome, etc.) that conveys a necessary helper function may also be used. These recombinant viruses may be produced in accordance with techniques already known and published in the art. A variety of adenovirus cell lines is available from ATCC (American Type Culture Collection) and is also commercially available. Alternatively, the sequences of many adenovirus cell lines are available from, e.g., public databases (e.g., PubMed, Genbank, etc.).

In the present invention, it is preferred to derive the AdV helper from a virus for the same species as the cultured cells. For example, when human cultured cells 293T are used, a human AdV-derived helper virus vector may be used. Commercially available vectors (e.g., Agilent Technologies, AAV Helper-Free System (Catalog No. 240071)) may be used as such AdV helper vectors.

In producing the rAAV virion of the present invention, various known methods including, e.g., the calcium phosphate method, lipofection method, electroporation method, etc. may be used in the method for transfecting one or more plasmids as described above to cultured cells. Such methods are described in, e.g., Molecular Cloning 3rd Ed., Current Protocols in Molecular Biology, John Wiley & Sons 1987-1997, etc.

3. Pharmaceutical Composition Comprising the rAAV Virion of the Present Invention

In a still further embodiment of the present invention, a pharmaceutical composition comprising the rAAV virion (rAAV vector) of the present invention is provided. Using the pharmaceutical composition comprising the rAAV virion of the present invention (hereinafter referred to as the present pharmaceutical composition), a gene can be introduced into nervous system cells of a subject with a high efficiency, and a method is provided in which a disease of interest can be treated with the introduced gene. The rAAV can pass through the blood-brain barrier in a living subject and hence, the rAAV of the present invention can be delivered to nervous system cells in the brain, spinal cord, etc. of a living subject through peripheral administration to the subject. That is, when the rAAV of the present invention is used, an administration route which requires more careful handling such as intraparenchymal administration is not required so that higher safety can be expected.

In one embodiment, the rAAV virion of the present invention preferably comprises a nervous system cell-specific promoter sequence and a therapeutic gene operably linked to the promoter sequence. The rAAV virion of the present invention may contain a gene which is useful for the treatment of neurological disorders (e.g., Parkinson's disease, Alzheimer's disease, triplet repeat disease, prion disease, amyotrophic lateral sclerosis, spinocerebellar degeneration, channel disease, epilepsy, etc.), inborn errors of metabolism (Wilson's disease, peroxisome disease, etc.), demyelinating disorders (multiple sclerosis, etc.), central neuron infectious diseases (e.g., HIV encephalitis, bacterial meningitis, etc.), vascular disorders (cerebral infarction, cerebral hemorrhage, spinal cord infarction), trauma (cerebral contusion, spinal cord injury, etc.), retinal disorders (age-related macular degeneration, diabetic retinopathy, etc.), and so on. Therefore, the useful treating gene is allowed to pass through the blood-brain barrier and to be incorporated into nerve cells in the brain, spinal cord or retina, e.g. the rAAV virion carrying such a therapeutic gene is included in the pharmaceutical composition of the present invention. These therapeutic genes may be a polynucleotide selected from those encoding the antibody, nerve growth factor (NGF), growth factor (HGF), acidic fibroblast growth factor (aFGF), etc. described above. The therapeutic gene of interest associated with Parkinson's disease includes, for example, an antisense polynucleotide, RNAi, etc. that down-regulate the expression of α-synuclein. The rAAV virion used to treat Alzheimer's disease can be produced by choosing, e.g., the polynucleotide encoding a single chain antibody capable of recognizing aggregated amyloid β protein. It can be expected to treat neurological disorders such as Parkinson's disease, Alzheimer's disease, etc., by peripheral administration of such rAAV virion to a subject. For example, the pharmaceutical composition of the present invention can reduce the expression level of α-synuclein, e.g., in nerve cells in the patient's brain and is useful for the treatment of Parkinson's disease. Furthermore, by expressing an antibody against aggregated amyloid β protein, the pharmaceutical composition can reduce the aggregated amyloid β protein in the patient's brain and is thus useful for the treatment of Alzheimer's disease.

When the pharmaceutical composition of the present invention is used, the composition may be administered, e.g., orally, parenterally (intravenously), intramuscularly, through the oral mucosa, rectally, intravaginally, subcutaneously, intranasally, by inhalation, etc., preferably, parenterally, and more preferably, intravenously. The active ingredient in the pharmaceutical composition of the present invention may be formulated alone or in combination therein, and may also be provided as a pharmaceutical preparation by formulation with a pharmaceutically acceptable carrier or an additive for a pharmaceutical preparation. In this case, the active ingredient of the present invention may be contained by, e.g., 0.1 to 99.9 wt % in the preparation.

Examples of the pharmaceutically acceptable carriers or additives which may be used include excipients, disintegrants, disintegration aids, binders, lubricants, coating agents, dyes, diluents, dissolution agents, dissolution aids, isotonic agents, pH regulators, stabilizers, etc.

Examples of the pharmaceutical preparations suitable for oral administration may include powders, tablets, capsules, fine granules, granules, liquid or syrup, etc. For oral administration, various excipients such as microcrystalline cellulose, sodium citrate, calcium carbonate, dipotassium phosphate and glycine may be employed in combination with various disintegrants such as starch and preferably corn, potato or tapioca starch, alginic acid and certain silicate complexes; and various granulation binders such as polyvinylpyrrolidone, sucrose, gelatin, gum arabic, etc. Additionally, lubricants such as magnesium stearate, sodium lauryl sulfate, talc, etc. are often very useful for tableting purposes. Such solid compositions may also be employed by encapsulation in gelatin capsules. Preferred materials in relation to this further may include lactose or milk sugar, as well as high molecular weight polyethylene glycols. When aqueous suspensions and/or elixirs are desired for oral administration, the active ingredient may be used in combination with various sweeteners or corrigents, coloring agents or dyes, and, if necessary, emulsifying and/or suspending agents as well, together with diluents such as water, ethanol, propylene glycol, glycerin, etc. and combinations thereof.

Examples of the pharmaceutical preparations suitable for parenteral administration include injections, suppositories, etc. For parenteral administration, solutions of the active ingredient of the present invention in either sesame or peanut oil or in aqueous propylene glycol solution may be employed. The aqueous solutions should be appropriately buffered (preferably pH of 8 or higher) depending upon necessity; it is first necessary to render the liquid diluent isotonic. Such a liquid diluent includes, for example, physiological saline. These aqueous solutions prepared are suitable for intravenous injection. On the other hand, the oily solutions are suitable for intra-articular, intra-muscular and subcutaneous injection. The preparation of all these solutions under sterile conditions can be readily accomplished by standard pharmaceutical techniques well known to those skilled in the art. Furthermore, the active ingredient of the present invention may also be administered topically to the skin, etc. In this case, topical administration is preferred by way of creams, jellies, gels, pastes, ointments and the like, in accordance with standard pharmaceutical practice.

The dose of the pharmaceutical composition of the present invention is not particularly limited, and an appropriate dose can be chosen depending on various conditions such as type of disease, age and symptoms of the patient, administration route, therapeutic goal, presence or absence of concurrent drugs, etc. The dose of the pharmaceutical composition of the present invention is, but not limited to, for example, 1 to 5,000 mg, and preferably 10 to 1,000 mg per day for an adult (e.g., body weight of 60 kg). The composition of such daily dosage may be administered daily in 2 to 4 divided doses. When vg (vector genome) is used as a dosage unit, the dose may be chosen from, but not limited to, e.g., the range from 10⁹ to 10¹⁴ vg, preferably, 10¹⁰ to 10¹³ vg, and more preferably, 10¹⁰ to 10¹² vg per body weight of 1 kg.

4. Method for Transferring Genes to a Living Subject Using the rAAV Virion of the Present Invention

In a still further embodiment, the present invention provides a method for transferring a gene to a nervous system cell in a living subject, which comprises using the rAAV virion of the present invention (hereinafter referred to as the method of the present invention). Specifically, the method of the present invention comprises the step of peripherally administering the rAAV virion of the present invention to a subject. The method of the present invention further comprises the step of delivering a therapeutic gene contained in the rAAV virion of the present invention to a nervous system cell in the brain, spinal cord, etc. The rAAV virion of the present invention is capable of passing through the blood-brain barrier of a living subject (including an adult and a fetus) as described above. Thus, administration routes like intracerebral administration that require more careful handling are not required, and higher safety can be expected.

In a still further embodiment, the rAAV virion of the present invention preferably comprises a recombinant viral genome comprising the nervous system cell-specific promoter sequence and a therapeutic gene operably linked to the promoter sequence (such a viral genome is packaged). As these therapeutic genes, a polynucleotide may be selected from those encoding the antibody, nerve growth factor (NGF), growth factor (HGF), acidic fibroblast growth factor (aFGF), etc., described above. In a still further embodiment of the present invention, the rAAV virion comprising a polynucleotide encoding a single chain antibody capable of recognizing, e.g., aggregated amyloid β protein is peripherally administered to a subject, whereby the aggregated amyloid β protein in the brain of the subject can be reduced so that it can be expected to treat Alzheimer's disease. Furthermore, it can be expected to treat (relieve, improve, repair, etc.) genetic defects (including congenital or acquired) in nerve cells, using the rAAV virion of the present invention.

5. Kit of the Present Invention

In a still another embodiment, the present invention provides a kit for producing the rAAV of the present invention. The kit may comprise, for example, (a) a first polynucleotide and (b) a second polynucleotide as described above. The first polynucleotide may contain, e.g., a polynucleotide encoding the protein of SEQ ID NOs: 8, 10 and 12. The second polynucleotide may or may not contain a therapeutic gene of interest, and preferably may contain various restriction enzyme cleavage sites used to incorporate such a therapeutic gene of interest.

The kit for producing the rAAV virion of the present invention further comprises any component described herein (e.g., an AdV helper, etc.). The kit of the present invention may further include instructions describing the protocols for producing the rAAV virion using the kit of the present invention.

Unless otherwise specified, all terms used herein are intended to refer to ordinary meanings as are generally understood by those skilled in the art.

EXAMPLES

The present invention is described below in more detail by referring to Examples but the scope of the invention should not be limited to the following Examples.

Materials and Methods

(1) Modification of AAV Coat (Capsid) Protein VP1

For 3 types of AAV, i.e., AAV serotype 1 (AAV1), AAV serotype 2 (AAV2) and AAV serotype 9 (AAV9), plasmids pAAV1-RC, pAAV2-RC and pAAV9-RC containing the nucleotide sequences encoding the respective VP1 capsid proteins were used as templates. These plasmids are derived from AAV3 Rep/VP described in the publication (Handa, et al., J Gen Virol, 81: 2077-2084, 2000) and contain the AAV3 Rep sequence (Muramatsu, et al., Virology 221, 208-217 (1996)). These nucleotide sequences of AAV VP1 were already reported to GenBank under Accession Nos. AF063497, AF043303 and AY530579, respectively (set forth in SEQ ID NOs: 1, 3 and 5, respectively). The primers shown below were synthesized, and the tyrosine (Y) residues were substituted with phenylalanine (F) residues which were located at position 445 of the AAV1 VP1 amino acid sequence (SEQ ID NO: 2), at position 444 of the AAV2 VP1 amino acid sequence (SEQ ID NO: 4) and at position 446 of the AAV9 VP1 amino acid sequence (SEQ ID NO: 6), using a Quick Change II XL site-directed mutagenesis kit (Stratagene). Plasmids pAAV1-yfRC, pAAV2-yfRC and pAAV9-yfRC containing the polynucleotides encoding the substituted amino acid sequences AAV1-yfVP1 (SEQ ID NO: 8), AAV2-yfVP1 (SEQ ID NO: 10) and AAV9-yfVP1-3 (SEQ ID NO: 12), respectively, were prepared. The plasmids pAAV1-yfRC, pAAV2-yfRC and pAAV9-yfRC all contained the nucleotide sequence (SEQ ID NO: 15) encoding AAV2 Rep.

(SEQ ID NO: 17) yfAAV1-F: 5′-CGACCAATACCTGTATTTCCTGAACAGAACTC-3′ (SEQ ID NO: 18) yfAAV1-R: 3′-GCTGGTTATGGACATAAAGGACTTGTCTTGAG-5′ (SEQ ID NO: 19) yfAAV2-F: 5′-CGACCAGTACCTGTATTTCTTGAGCAGAACAAAC-3′ (SEQ ID NO: 20) yfAAV2-R: 3′-GCTGGTCATGGACATAAAGAACTCGTCTTGTTTG-5′ (SEQ ID NO: 21) yfAAV9-F: 5′-CGACCAATACTTGTACTTTCTCTCAAAGAC-3′ (SEQ ID NO: 22) yfAAV9-R: 3′-GCTGGTTATGAACATGAAAGAGAGTTTCTG-5′

(2) Production of rAAV Vector

(a) Production of Vector Genome Plasmid

Synapsin I (SynI) promoter (GenBank Accession No. M55300.1, SEQ ID NO: 23) was used as a nerve cell-specific promoter, or myelin basic protein (MBP) promoter (GenBank Accession No. M63599, SEQ ID NO: 24) as an oligodendrocyte-specific promoter. Cytomegalovirus enhancer/chicken β-actin (CAG) promoter was used as a control (Niwa H., et al., Gene 108:193-200, 1991). These promoters and the green fluorescence protein (GFP) nucleotide sequence (TAKARA Product Code Z2468N) were inserted between the hairpin DNA sequences, called inverted terminal repeats (ITRs), at the 5′ and 3′ ends of the plasmid pAAV3 containing the AAV serotype 3 (AAV3) DNA sequence, constructing three plasmids pAAV-SynI-GFP, pAAV-MBP-GFP and pAAV-CAG-GFP. The basic structures of these plasmids are described in Li et al., Mol Ther 13:160-166. 2006.

(b) Transfection to HEK293 Cells

<Day 1>

HEK293 cells of 1.5×10⁶ were plated in a 225 cm² flask and incubated in 10% FCS-DMEM/F12 medium under 5% CO₂ at 37° C.

<Day 3>

Transfection was performed by the calcium phosphate method. The following 10 combinations of the plasmids (AAV vector plasmids+AAV helper plasmids) and the helper plasmids pHelpers containing the adenovirus (AdV) nucleotide sequence (AAV Helper-Free System from Agilent Technologies (Catalog No. 240071)) in an amount of 25 μg each (75 μg in total) were mixed in 0.3M CaCl₂.

TABLE 1 Sample AAV vector AAV helper AdV helper produced rAAV ID genome plasmid plasmid plasmid virion 1 pAAV-CAG-GFP1 pAAV1-RC pHelper AAV1-CAG-GFP1 2 pAAV-CAG-GFP1 pAAV1-yfRC ↑ yfAAV1-CAG-GFP1 3 pAAV-SynI-GFP1 pAAV1-RC ↑ AAV1-SynI-GFP1 4 pAAV-SynI-GFP1 pAAV1-yfRC ↑ yfAAV1-SynI-GFP1 5 pAAV-SynI-GFP1 pAAV2-RC ↑ AAV2-SynI-GFP1 6 pAAV-SynI-GFP1 pAAV2-yfRC ↑ yfAAV2-SynI-GFP1 7 pAAV-CAG-GFP1 pAAV9-RC ↑ AAV9-CAG-GFP1 8 pAAV-CAG-GFP1 pAAV9-yfRC ↑ yfAAV9-CAG-GFP1 9 pAAV-SynI-GFP1 pAAV9-yfRC ↑ yfAAV9-SynI-GFP1 10 pAAV-MBP-GFP1 pAAV9-yfRC ↑ yfAAV9-MBP-GFP1

Subsequently, 2×HBS (80 mM NaCl, 50 mM Hepes buffer, 1.5 mM Na₂HPO₄ (pH7.10)) was added to each mixture to prepare the DNA-calcium phosphate complex. The culture medium in the flask was replaced with the medium supplemented with the DNA-calcium phosphate complex. After incubation for several hours, the medium was exchanged.

<Day 6>

Resultant 10 types of recombinant virus virions (“rAAV virion” in the table above) by the above combinations were recovered. By adding 0.5 mM EDTA, the cells were removed from the culture dish and suspended in TBS (100 mM Tris HCl, pH 8.0, 150 mM NaCl). Freezing/thawing was repeated 3 times using dry ice-ethanol and a water bath at 37° C. to lyse the cells. After centrifugation at 10,000×g for 10 minutes, the supernatant was recovered to remove coarse cell debris.

(c) Purification of Virus Vector

According to the following procedure, cesium chloride CsCl density gradient ultracentrifugation was performed to purify the rAAV vector. CsCl of 1.5 M and 1.25 M was layered in an ultracentrifugation tube to form a density gradient. The rAAV vector-containing cell lysate was layered, followed by ultracentrifugation (30,000 rpm, 2.5 hours). The refractive index was measured and the fraction containing the rAAV vector with RI of 1.365 to 1.380 was recovered. This fraction was layered again over a CsCl solution and ultracentrifuged (36,000 rpm, 2.5 hours) to give the rAAV-containing fraction.

(d) Measurement of Virus Vector Titer (Real Time PCR)

A 10⁻² to 10⁻⁶ dilution series of the purified rAAV was prepared. The primer set (SEQ ID NOS: 25 and 26) containing the GFP sequence as a standard was used for quantification on the Applied Biosystems 7900HT Fast Real Time PCR System (Applied Biosystems).

Example 1

1. Gene Transfer to Nerve Cells in the Brain of Adult Mice

(1) Intracardial Administration of rAAV Vector in Mice

Animals used were 30 male C57BL6 adult mice at 4 months old after birth (3 mice for each vector). After anesthesia by intraperitoneal administration of 200 μl per 30 g body weight of Nembutal, the mice were fixed on a stereotaxic apparatus for small animals. The mice were injected with each dilution of the above vectors diluted in PBS at 2×10¹² vg (dose volume: 100 μl), using a 1 ml insulin syringe via percutaneous puncture of the left ventricle. The mice were observed in a cage placed on a heating pad until they awoke from anesthesia. Thereafter, the mouse cage was put back in a rack for infected animals.

(2) Immunohistochemistry

Under deep anesthesia, mice were infused with PBS and then with ice-chilled 4% PFA. The brain and spinal cord were dissected and then postfixed for 4 hours in 4% PFA. A slice (40 μm) of brain coronal sections in the range (3.2 mm) from 0.7 mm anterior to 2.5 mm posterior from the bregma was prepared. Also, a slice (40 μm) of horizontal cross section of the cervical spinal cord was prepared. Blocking was performed for 1 hour in 0.3% Triton X-100/PBS containing 2% Mouse IgG Blocking solution (M.O.M Kit; Vector Laboratories, Burlingame, Calif., USA), followed by incubation with NeuN (1:100, mouse anti-Neuronal nuclei monoclonal antibody; Chemicon, Temecula, Calif., USA) and GFP (1:1000, rabbit anti-GFP polyclonal antibody; Abcam, Cambridge, Mass., USA) overnight at 4° C. Subsequently, the slices were incubated with Alexa Fluor (registered trademark) 594 anti-mouse IgG and then with Alexa Fluor (registered trademark) 488 anti-rabbit IgG (1:500, Invitrogen, Carlsbad, Calif., USA) at room temperature for 2 hours to visualize them. Observation was performed under a confocal laser microscope (TCS NT; Leica, Heidelberg, Germany) to count GFP and NeuN-positive cells per 0.04 mm³ in the cerebral cortices (1 m×1 mm×40 μm) in slices at 200 μm intervals and per spinal cord slice. Also, GFP-positive cells in the spinal cord were identified by GFP/ChAT double immunofluorescence staining described below. After blocking in a similar manner, a slice of the cervical spinal cord was incubated with ChAT (diluted in 1:100, mouse anti-ChAT polyclonal antibody; Chemicon, Temecula, Calif., USA) and GFP (diluted in 1:1000, Abcam) at 4° C. overnight. Thereafter, the slice was incubated with Alexa Fluor (registered trademark) 594 anti-mouse IgG and then with Alexa Fluor (registered trademark) 488 anti-rabbit IgG (1:500, Invitrogen) at room temperature for 2 hours to visualize them. The slice was then observed as in the GFP/NeuN double staining.

For GFP/Olig2 double immunofluorescence staining, the slice was blocked in 0.3% TritonX-100/PBS containing 3% goat serum, followed by incubation with Olig2 (diluted in 1:50, rabbit anti-Olig2 polyclonal antibody; IBL, Takasaki, Gunma, Japan) at 4° C. overnight. Thereafter, the slice was incubated with Alexa Fluor (registered trademark) 594 anti-mouse IgG and then with Alexa Fluor (registered trademark) 488 anti-rabbit IgG (diluted in 1:500, Invitrogen) at room temperature for 2 hours, respectively. Observation was performed as in the other immunofluorescent staining to count the cells emitting fluorescence.

2. Results

(1) Among the combinations shown in TABLE 1 above, no GFP expression was observed in nerve cells of the cerebral cortex and spinal cord in the combinations that produced the following 6 species of rAAV vectors.

-   -   AAV1-CAG-GFP (Sample ID: 1),     -   yfAAV1-CAG-GFP (Sample ID: 2),     -   AAV1-SynI-GFP (Sample ID: 3),     -   AAV2-SynI-GFP (Sample ID: 5),     -   yfAAV2-SynI-GFP (Sample ID: 6),     -   AAV9-CAG-GFP (Sample ID: 7).

(2) In the combination of yfAAV1-SynI-GFP (Sample ID: 4), the GFP expression was observed in nerve cells of the brain and spinal cord, while no positive cells were detected with the combination of AAV1-SynI-GFP (Sample ID: 3) (FIG. 1). The results thus revealed that highly efficient gene transfer into nerve cells in the brain can be achieved by replacing tyrosine (Y) 445 in the capsid protein VP1 of AAV1 with phenylalanine (F).

(3) In yfAAV9-CAG-GFP (Sample ID: 8), a few nerve cells were observed to express GFP, while most of the GFP-positive cells were glial cells, not nerve cells. In contrast, in yfAAV9-SynI-GFP (Sample ID: 9), approximately 4-fold higher counts of the GFP-positive nerve cells were seen (FIGS. 2A and 2B and FIG. 3). In yfAAV9-MBP-GFP, many GFP-positive oligodendrocytes were seen (FIG. 2C). The results thus indicate that highly efficient gene transfer into nerve cells in the brain by peripheral administration of the rAAV vector can be achieved by using the nerve cell-specific promoter or oligodendrocyte-specific promoter sequence.

When the rAAV virion was not administered peripherally but was injected directly into the brain, transduction efficiencies into nerve cells are sufficiently high even in case that the CAG promoter was used; it was specifically shown that the gene expression level was 2 to 4 times larger than Syn I promoter (Hioki et al., Gene Ther 14: 872-882, 2007, etc.). However, when the rAAV virion of the present invention was intravascularly administered, most of the gene expression was found in glia-like cells, not in nerve cells, for the rAAV virion where the CAG promoter was used. Also when the rAAV vector in which the conventional CMV promoter was used, the gene was introduced mostly in glia-like cells, not in nerve cells, in the adult.

Meanwhile, the gene expression level of nerve cell-specific promoter SynI in nerve cells was more prominent than that of the CAG promoter. Accordingly, the results above demonstrate that nerve cell-specific promoters such as SynI, etc. are more advantageous as a promoter used in combination with the rAAV virion of the present invention rather than generally strong, non-specific promoters such as the CAG promoter, etc., and show synergistic effects on gene transfer into nerve cells through peripheral administration in these combinations.

In the spinal cord, 24±3.5 of nerve cells per slice of the cervical spinal cord in which GFP and NeuN were positive were observed. In addition, 4 to 5 cells in the GFP-positive cells in each slice were ChAT-positive motor nerve cells (FIG. 4). Accordingly, the results demonstrate that by using the nerve cell-specific promoter (SynI) or oligodendrocyte-specific promoter (MBP), the gene can be stably transferred to nerve cells and oligodendrocytes in the adult mouse brain and spinal cord through peripheral administration.

3. Summary

Based on the foregoing results, it was demonstrated that by substituting the tyrosine (Y) residue at each of positions 445/444/446 in the wild type AAV1/2/9 capsid VP1 protein, respectively, with a phenylalanine (F) residue and by using the SynI promoter sequence or MBP promoter sequence as a nerve cell-specific promoter in combination with a therapeutic gene of interest, the rAAV vector of the present invention was able to pass through the blood-brain barrier through peripheral administration to adult mice and finally transfer the gene to nervous system cells in the brain and spinal cord with a high efficiency.

Example 2

Gene Transfer to Fetal Brain Through Peripheral Administration to Mother Mice

It is reported that a gene was transferred to fetal mice by intraamniotically administering the rAAV vector to mother mice (RAHIM ET AL., FASEB Journal, pp 1-14, Vol. 25 Oct. 2011). Therefore, gene transfer to fetal mice by peripheral administration of the rAAV vector of the present invention to mother mice was examined

Materials and Methods

-   -   rAAV Vector: yfAAV9-SynI-AcGFP1 (Sample ID: 9)     -   Titer: 1.3×10¹³ vector genome/ml     -   Dosing Volume: 50 μl

Method of Administration

On Day 13 of pregnancy, the rAAV vector above was given to mother mice (3) by intracardial administration. For their offspring mice (9 in total), the coronal section slices (40 μm thick) from the area around the hippocampus of each brain on Day 1 and Weeks 3, 4 and 11 after birth were prepared through infusion and fixation with 4% paraformaldehyde (PFA). GFP expressed in nerve cells in each of the sliced specimens prepared was detected, as described above.

Results

In 20 sliced specimens in total from the 5 mice, expressed GFP was assayed; 4.6 cells/slice on average were observed to be GFP-positive (FIG. 5). The results reveal that the rAAV vector of the present invention was able to transfer the gene to nerve cells in the fetal brain even through peripheral administration to the mother mice.

Example 3

Expression Regulation by Aromatic Amino Acid Decarboxylase (AADC) In Brain Nerve Cells Using the Recombinant AAV Vector: yfAAV9-SynI-GFP-miAADC

It was investigated to determine if the rAAV vector of the present invention is useful as a therapeutic vector that can regulate the expression of endogenous gene, by incorporating miRNA, etc. into viral genome. Specific procedures are as follows: an rAAV vector was constructed from yfAAV9-SynI-GFP (Sample ID: 9) as a basis to contain yfAAV9 as a capsid protein and express miRNA against mouse aromatic amino acid decarboxylase (AADC) and green fluorescent protein (GFP) by nerve cell-specific Synapsin I promoter. The vector was given to mice and examined if the vector could decrease AADC in the brain nerve cells.

For the miRNA used, the sequence described below was synthesized to obtain 5′-TGCCTTTATGTCCTGAATT-3′ (SEQ ID NO: 27) corresponding to the nucleotide positions 831 to 851 of mouse AADC (GenBank accession No. NM_(—)016672).

(SEQ ID NO: 28) 5′-GAATTCAGGACAGATAAAGGCAGTTTTGGCCACTGACTGACTGCCTT TATGTCCTGAATT-3′

This sequence was incorporated into the downstream of GFP gene in the rAAV vector genome plasmid pAAV-SynI-GFP designated as Sample ID: 9 in TABLE 1 above to construct pAAV-SynI-GFP-miAADC (cf., SEQ ID NO: 29). As in Sample ID: 9, both the AAV helper plasmid pAAV9-yfRC and AdV helper plasmid pHelper were used together to construct the rAAV virion yfAAV9-SynI-GFP-miAADC.

Materials and Procedures

-   -   rAAV Vector: yfAAV9-SynI-GFP-miAADC     -   Titer: 1.7×10¹⁴ vector genome/ml     -   Adult mice: C57BL/6J, 10 weeks old, 4 male mice     -   Intracardial administration: 50 μl/mouse

Procedures for Brain Tissue Analysis

The mice were infused and fixed with 4% paraformaldehyde (PFA) 2 weeks after administration of the rAAV vector. The brain was then removed and fixed for 4 hours followed by 10%→20%→30% sucrose, preparing coronal section slices of 40 μm thick on slide glasses. For immunostaining, the sliced specimen was blocked with 3% normal goat serum. Then, rabbit anti-AADC (anti-AADC, diluted to 1:5000, provided with courtesy by Dr. Toshiharu Nagatsu, Nagoya University) and murine anti-tyrosine hydroxylase (anti-TH) (Dia Sorin, diluted to 1:800) as primary antibodies were reacted with the sliced specimen at 4° C. overnight. Secondary antibodies including Alexa Fluor (registered trademark) 594 anti-rabbit IgG and Alexa Fluor (registered trademark) 405 anti-mouse IgG (both from Life Technologies, diluted to 1:1000) were both reacted with each sliced specimen at room temperature for 2 hours. Thereafter, this antibody was reacted with each sliced specimen at room temperature for an hour, using Alexa Fluor (registered trademark) 488 conjugate anti-GFP (Life Technologies, diluted to 1:400). The respective fluorescent substances in the sliced specimens were visualized by a confocal laser scanning microscope (FV10i; Olympus, Tokyo) (FIG. 6).

Results

In FIG. 6, left (anti-GFP), 5 GFP-positive cells were observed in the substantia nigra pars compacta. It is thus confirmed that the rAAV vector of the present invention was able to transfer the gene to the nerve cells as in the Examples above. The results from these nerve cells reacted with anti-AADC exhibited almost the same reaction as the background; the cells were not significantly colored (FIG. 5, center, anti-AADC). Consequently, the expression of AADC in the brain nerve cells was significantly decreased by using the rAAV vector of the present invention. For control, it was confirmed that expression of intracellular protein tyrosine hydroxylase (TH) was maintained (FIG. 5, right, anti-TH). Based on the foregoing, the results showed that the rAAV vector of the present invention is capable of transferring genes to nerve cells in the brain and thus is useful as a therapeutic vector by introducing miRNA into viral genome to suppress the expression of endogenous genes, or the like.

INDUSTRIAL APPLICABILITY

The recombinant adeno-associated virus (rAAV) virion of the present invention is capable of passing through the blood-brain barrier and thus capable of transferring genes to nervous system cells through easy administration means including peripheral administration. Therefore, the pharmaceutical composition capable of gene transfer into nervous system cells can be provided by incorporating the polynucleotide encoding a useful protein including, e.g., an antibody and a neurotropic factor into the present recombinant vector. The recombinant vector of the present invention, in which a gene encoding, e.g., an antibody against amyloid 13 protein aggregate as the cause of Alzheimer's disease is incorporated, can provide a safer therapeutic means for Alzheimer's disease. The viral particles for introducing a gene of interest into nervous system cells can be produced by using the method for preparing viral particles of the present invention and/or the kit of the present invention.

SEQUENCE LISTING FREE TEXT

-   SEQ ID NO: 1 Wild-type AAV1-derived capsid protein AAV1-VP1     nucleotide sequence (GenBank: NC_(—)002077.1) -   SEQ ID NO: 2 Wild-type AAV1-derived capsid protein AAV1-VP1 amino     acid sequence (GenBank: NC_(—)2077.1) -   SEQ ID NO: 3 Wild-type AAV2-derived capsid protein AAV2-VP1     nucleotide sequence (GenBank: NC_(—)001401.2) -   SEQ ID NO: 4 Wild-type AAV2-derived capsid protein AAV2-VP 1 amino     acid sequence (GenBank: NC_(—)001401.2) -   SEQ ID NO: 5 Wild-type AAV9-derived capsid protein AAV9-VP1     nucleotide sequence (GenBank: AY530579.1) -   SEQ ID NO: 6 Wild-type AAV9-derived capsid protein AAV9-VP1 amino     acid sequence (GenBank: AY530579.1) -   SEQ ID NO: 7 AAV1-derived capsid protein mutant AAV1-yfVP1     nucleotide sequence -   SEQ ID NO: 8 AAV1-derived capsid protein mutant AAV1-yfVP1 amino     acid sequence -   SEQ ID NO: 9 AAV2-derived capsid protein mutant AAV2-yfVP1     nucleotide sequence -   SEQ ID NO: 10 AAV2-derived capsid protein mutant AAV2-yfVP1 amino     acid sequence -   SEQ ID NO: 11 AAV9-derived capsid protein mutant AAV9-yfVP1     nucleotide sequence -   SEQ ID NO: 12 AAV9-derived capsid protein mutant AAV9-yfVP1 amino     acid sequence -   SEQ ID NO: 13 AAV3-derived 5′ end ITR nucleotide sequence (GenBank     NC_(—)001729-derived) -   SEQ ID NO: 14 AAV3-derived 3′ end ITR nucleotide sequence -   SEQ ID NO: 15 AAV2-derived rep gene nucleotide sequence -   SEQ ID NO: 16 AAV2-derived Rep protein amino acid sequence -   SEQ ID NO: 17 Mutagenesis primer 1 (yfAAV1-F) nucleotide sequence -   SEQ ID NO: 18 Mutagenesis primer 2 (yfAAV1-R) nucleotide sequence -   SEQ ID NO: 19 Mutagenesis primer 3 (yfAAV2-F) nucleotide sequence -   SEQ ID NO: 20 Mutagenesis primer 4 (yfAAV2-R) nucleotide sequence -   SEQ ID NO: 21 Mutagenesis primer 5 (yfAAV9-F) nucleotide sequence -   SEQ ID NO: 22 Mutagenesis primer 6 (yfAAV9-R) nucleotide sequence -   SEQ ID NO: 23 Synapsin I promoter sequence (GenBank: M55300.1) -   SEQ ID NO: 24 Myelin basic protein promoter sequence (GenBank:     M63599 (human)-derived) -   SEQ ID NO: 25 GFP detection primer 1 nucleotide sequence -   SEQ ID NO: 26 GFP detection primer 2 nucleotide sequence -   SEQ ID NO: 27 Nucleotide sequence designed for 831-851 nucleotides     of murine aromatic amino acid decarboxylase (AADC: GenBank accession     No. NM_(—)016672) -   SEQ ID NO: 28 Nucleotide sequence to form miRNA against murine     aromatic amino acid decarboxylase (AADC) -   SEQ ID NO: 29 Nucleotide sequence to express GFP and miRNA (SEQ ID     NO: 28) against murine aromatic amino acid decarboxylase (AADC) 

1. A recombinant adeno-associated virus virion comprising: (a) a capsomere which comprises a protein comprising an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 2, 4 or 6, wherein at least one of surface-exposed tyrosine residues in the amino acid sequence is substituted with another amino acid residue, wherein the protein is capable of forming a virus virion, and (b) a polynucleotide packaged in said capsomere which comprises a nervous system cell-specific promoter sequence and a nucleotide sequence operably linked to the promoter sequence.
 2. The virus virion according to claim 1, wherein the protein comprises an amino acid sequence in which at least the tyrosine residue at position 445 in SEQ ID NO: 2, the tyrosine residue at position 444 in SEQ ID NO: 4 or the tyrosine residue at position 446 in SEQ ID NO: 6 is substituted.
 3. The virus virion according to claim 1, wherein the tyrosine residue is substituted with a phenylalanine residue.
 4. The virus virion according to claim 1, wherein the protein comprises: the amino acid sequence of SEQ ID NO: 8, 10 or 12, or an amino acid sequence in which 1 to several amino acids are deleted, substituted, inserted and/or added at positions other than positions 444 to 446 in the amino acid sequence of SEQ ID NO: 8, 10 or 12, and wherein the protein is capable of forming a virus virion.
 5. The virus virion according to claim 1, wherein the 5′ and 3′ ends of the polynucleotide contain the 5′ and 3′ end-inverted terminal repeat (ITR) sequences derived, respectively, from AAV1, AAV2, AAV3 or AAV4.
 6. The virus virion according to claim 1, wherein the 5′ and 3′ ends of the polynucleotide contain the nucleotide sequences of SEQ ID NO: 13 and SEQ ID NO: 14, respectively.
 7. The virus virion according to claim 1, wherein the polynucleotide has a full length of approximately 2 to 6 kb and is a single stranded DNA which is a sense strand or an antisense strand.
 8. The virus virion according to claim 1, wherein the promoter sequence is selected from the group consisting of a synapsin I promoter sequence, a myelin basic protein promoter sequence, a neuron-specific enolase promoter sequence, a calcium/calmodulin-dependent protein kinase II (CMKII) promoter sequence, a tubulin αI promoter sequence, platelet-derived growth factor β chain promoter sequence, a glial fibrillary acidic protein (GFAP) promoter sequence, a L7 promoter (cerebellar Purkinje cell specific promoter) sequence and a glutamate receptor delta 2 promoter (cerebellar Purkinje cell specific promoter) sequence sequence.
 9. The virus virion according to claim 7, wherein the promoter sequence comprises the polynucleotide as set forth in SEQ ID NO: 23 or SEQ ID NO:
 24. 10. The virus virion according to claim 7, wherein the nucleotide sequence operably linked to the promoter sequence encodes a protein selected from the group consisting of an antibody, a nerve growth factor (NGF), a growth factor (HGF), an acidic fibroblast growth factor (aFGF), a basic fibroblast growth factor (bFGF), a glial cell line-derived neurotrophic factor (GDNF), an aromatic amino acid decarboxylase (AADC) and an amyloid β degrading protease (Neprilysin).
 11. The virus virion according to claim 7, wherein the nucleotide sequence operably linked to the promoter sequence expresses dsRNA, siRNA, shRNA or miRNA against the aromatic amino acid decarboxylase (AADC) or α-synuclein.
 12. The virus virion according to claim 9, wherein the antibody is an antibody against aggregated amyloid β protein.
 13. The virus virion according to claim 1, which is capable of passing through the blood-brain barrier of a subject.
 14. The virus virion according to claim 1, wherein the virus virion is an adeno-associated virus vector.
 15. A pharmaceutical composition comprising the virus virion according to claim
 1. 